1. Field of the Invention
The present invention relates to a lens apparatus used for a photographing apparatus such as a television camera. More particularly, the invention relates to a lens apparatus used for a virtual system which synthesizes an actually shot (photographed) picture with a computer graphic (virtual picture).
2. Description of the Related Art
A television lens has conventionally been able to create a desired picture scene by electrically or manually operating and moving an optical movable member such as a zoom lens, a focus lens, an iris mechanism or an extender to cause an optical change. FIG. 10 is a schematic system diagram of a television lens. Referring to FIG. 10, a reference numeral 100 denotes a television lens, reference number 120 denotes a television camera to which the television lens 100 is fixed, reference number 121 denotes a zoom demand connected for performing zooming of the television lens 100, and reference number 122 denotes a focus demand connected for performing focusing of the television lens 100. Reference numerals 123 and 124 respectively denote demand connectors for connecting the zoom demand 121 and the focus demand 122 to the television lens 100. In the television lens operated with this configuration, a potentiometer or a rotary encoder is connected to the movable member, and used as a position detection unit of the movable member for servo driving or position displaying. The television lens is classified into a highly accurate large lens used for a studio or the like, and a highly portable handy lens designed to be used outdoors or on a shoulder. For the large lens, a digital encoder for outputting a digital two-phase signal is used as a position detection unit. For the handy lens, a potentiometer that outputs an analog voltage is generally used.
On the other hand, a system called a virtual system for synthesizing an actually shot picture with a computer graphic picture associated therewith has actively been operated (Japanese Patent Application Laid-Open Nos. 2003-248650, 2002-32289, and 2001-202530). In these systems, the television lenses such as the large lens and the handy lens are used.
In the virtual system for synthesizing pictures, a signal (indicating a zoom position, a focus position or the like) from the position detection unit linked with the movable member of the television lens is passed to the system. Accordingly, a computer graphic matched with a size of an actually shot picture and a focal position can be created by a computer in the system, and pictures can be synthesized without any uncomfortable feelings even when the zoom, the focus or the like is operated in real time.
Conventionally, there has been no dedicated or standardized method of connecting the television lens to the virtual system. The system has been completed by using existing components of the television lens side or reconstructing the television lens side in response to a request from the virtual system side. In the existing system, for connection between the television lens and the virtual system, there are three connection methods respectively based on a digital pulse train, an analog voltage signal, and data communication. The three methods will be described below.
FIG. 11 is a block diagram illustrating an operation of the virtual system in the lens on which the digital encoder is mounted as a position detection unit. Referring to FIG. 11, a reference numeral 100 denotes a television lens, reference numeral 101 denotes a CPU which is a control unit for controlling the television lens 100, reference numeral 102 denotes a DA converter for writing a command value when zoom driving is performed from the CPU 101, reference numeral 103 denotes a power amplifier for amplifying power of a command from the DA converter 102, reference numeral 104 denotes a motor driven by the power amplifier 103, reference numeral 105 denotes a zoom lens connected to the motor 104 for varying the zoom, reference numeral 109 denotes a zoom digital encoder which is a zoom position detection unit linked with the zoom lens 105, and reference numeral 110 denotes a counter for counting a two-phase pulse of the zoom digital encoder 109 to set a zoom position. FIG. 11 shows a configuration of the zoom of the television lens. However, the focus, the iris, and the extender are also similar in configuration to the zoom. With this configuration, when a command comes from the command apparatus (zoom demand) 121 connected to the television lens 100, the CPU 101 performs comparison/arithmetic operation with a current zoom position from the counter 110 to calculate a new zoom command position, and writes a result thereof in the DA converter 102. Accordingly, the CPU 101 can perform zoom position control. The two-phase pulse from the zoom digital encoder 109 is input as a zoom position signal 301 to a virtual system 200 described below. A reference numeral 200 denotes the virtual system to which the zoom position signal 301 from the television lens 100 is inputted, reference numeral 202 denotes a counter for calculating a position of the zoom lens 105 from the zoom position signal 301, and reference numeral 201 denotes a CPU for fetching a focus position, an iris position and an extender position from a focus counter (not shown) in addition to a zoom position from the counter 202, and a picture signal from a television camera (not shown) connected to the television lens 100. A computer graphic screen created in the virtual system 200 is calculated from the zoom, focus, iris and encoder positions inputted by the two-phase pulse from the television lens 100, processed to match the picture signal of the television camera, and then synthesized with the picture signal of the television camera to complete a virtual picture (synthesized picture) of no uncomfortable feeling. FIG. 12 shows in detail an interface signal 301 of a two-phase pulse for interconnecting the television lens 100 and the virtual system 200. Relative position data and absolute position data (shown) are calculated based on a digitized phase signal. Thus, the encoder used for servo control is used for connecting the lens having the digital encoder mounted thereon to the virtual system, and the signal is passed to the virtual system to enable picture synthesis. For this purpose, however, a reconstruction has been necessary for using the encoder output for the servo control and putting it out of the television lens.
Next, FIG. 13 is a block diagram illustrating an operation of the virtual system in the television lens on which a potentiometer is mounted in place of the digital encoder. Different from the configuration of the digital encoder 109 and the counter 110 shown in FIG. 11, a position detection unit of the zoom lens 105 is a potentiometer 106 based on an analog signal, and accordingly an operational amplifier 107 and an AD converter 108 are provided. In addition, though not shown, a focus, an iris and an extender are also similar in configuration to those described above. The virtual system 200 includes an operational amplifier 203 for interface alignment and an AD converter 204 in place of the counter 202. With this configuration, an interface signal between the television lens 100 and the virtual system 200 is an analog voltage signal shown in FIG. 14. Thus, the potentiometer for servo control is used for connecting the television lens having the potentiometer mounted thereon in place of the existing digital encoder to the virtual system, and a signal is passed to the virtual system to enable picture synthesis. For this purpose, however, a reconstruction has been necessary for using the potentiometer output used for the servo control and putting it out of the television lens.
Next, FIG. 15 is a block diagram illustrating an operation of the virtual system based on data communication performed in response to a request of the virtual system side. Different from FIG. 11, FIG. 15 shows a case in which the signal from the digital encoder 109 is not directly passed to the counter 202 in the virtual system 200, but a value of the counter 110 is read by the CPU 101 in the lens, and position information of the zoom, the focus or the like is passed to a communication processing unit 205 in the CPU 201 of the virtual system side through data communication by a communication processing unit 112 in the CPU 101 of the lens, thereby enabling creation of a virtual picture (synthesized picture). For the connection to the virtual system through the data communication, however, a dedicated communication line must be provided in addition to a communication line originally used for communication between the television lens and the demand, and a reconstruction has been necessary for a standard lens.
As described above, in the conventional example, there is no standard connection means (interface) for facilitating the connection with the virtual system. Accordingly, hardware and software reconstructions have been necessary for the standard television lens. Especially, reasons that the television lens cannot have standard connection means (interfaces) are a limitation placed on connection means (interfaces) depending on types of the position detection unit of the television lens, a necessity of connection means in the data communication based on dedicated communication protocol depending on a request of the virtual system side, and the like. Another problem is that additional costs and a development period are necessary because the reconstructions and the like must be made. EP-A2-989747 (corresponding to JP-A-2000-106650) discloses the information transmission of input/output signal to the virtual system by both a digital method and communication method for synthesizing the shot picture.